High-efficiency heat exchanger and high-efficiency heat exchange method

ABSTRACT

A high-efficiency heat exchanger adaptable for a heat exchange target fluid having high purity. A heat exchanger has a flow passage through which a heat exchange target fluid flows, and a heat transfer structure that is contacted with the heat exchange target fluid flowing through the flow passage, thus performing heat-transfer type heat exchange through a contact surface of the heat transfer structure with the heat exchange target fluid. The contact surface of the heat transfer structure with the heat exchange target fluid is made of a material stable against the heat exchange target fluid. The heat transfer structure includes heat conductors made of a material having a high thermal conductivity. The heat conductors are mounted near the contact surface of the heat transfer structure with the heat exchange target fluid at positions where the heat conductors are not contacted with the heat exchange target fluid.

TECHNICAL FIELD

The present invention relates to heat exchange technology having nolimitations in application fields. In particular, the present inventionis useful not only for heat exchange of gases or liquids of corrosivesubstances, such as acids and alkalis, but also for temperature controlof high-purity water, high-purity silicon compounds used inmanufacturing semiconductors, etc. Thus, the present invention iseffective in solving the problems with corrosion of devices, etc. andcontamination of high-purity substances, which may occur during the heatexchange, and in realizing an improvement of a heat exchange rate.

In other words, the present invention can provide a heat exchanger and aheat exchange method, which ensure high efficiency in general technicalfields where temperature adjustment, such as cooling and heating, ofsubstances are needed, while suppressing corrosion of devices andcontamination caused by impurities.

It is to be noted that, in this Description, not only an exothermicsource, but also an endothermic source are called a “heat source” insome cases. The term “fluid” used in this Description involves asubstance that causes a phase change (e.g., a phase change from liquidto gas) with heating or heat absorption.

BACKGROUND ART

A heat exchanger is a device in which two objects having differenttemperatures are directly or indirectly contacted with each other toheat or cool one of the objects through heat transfer. The heatexchanger is used in cooling steps, heating steps, and refrigeration forindustrial purposes in various fields including a boiler, a steamgenerator, food production, production of chemicals, cold storage, andso on.

Usually, the heat exchanger has a structure depending on characteristicsof a substance to be subjected to heat exchange (i.e., a heat exchangetarget substance). For example, in a heat exchanger for chemicals whereheat exchange is performed with respect to highly-corrosive chemicalssuch as hydrofluoric acid, nitric acid, and sulfuric acid,highly-corrosive fluids such as strong acids and alkalis need to beheated and cooled by employing a heat exchanger having resistance to thechemicals. In that case, heat exchange is typically performed byindirect heating in which a contact portion made of a resin materialthat is less affected by acids or alkalis is immersed in a heat medium.

FIG. 1 is a schematic view illustrating typical indirect heat exchange.While a heat exchange target fluid (e.g., acid, alkali, or water) isconveyed through a resin-made pipe 1 from an inlet 2 to an outlet 3,heat exchange is performed between the fluid and a heat medium 4, ofwhich temperature is adjusted by a heat source 5, through the resin-madepipe 1. Such a method can improve a heat exchange rate by increasing asurface area of the resin-made pipe 1 contacting with the heat medium 4,e.g., by increasing a length of the pipe 1 immersed in the heat medium4. However, the cost of an apparatus, including a device for adjusting afluid temperature in the heat source, containers, etc., may be expensivein some cases. FIG. 2 illustrates a typical example of direct heating inwhich heat exchange is performed directly with respect to a heat sourcewithout intervention of a heat medium. Direct heat exchange is performedby holding a heat source 5 in contact with a pipe 1 made of a materialthat has high resistance to the heat exchange target fluid and that hasgood temperature characteristics.

In any type of heat exchange, the following points are required;apparatus components, including the conveying pipe, are not corroded bythe heat exchange target fluid or the heat exchange medium, the heatexchange fluid is not contaminated during a heat exchange step, and theheat exchange is performed at high efficiency.

In consideration of those requirements, the conveying pipe is coatedwith a resin or a ceramic to protect the conveying pipe to be notaffected, e.g., corroded, by the heat exchange target fluid or the heatexchange medium.

For example, there is proposed a heat transfer pipe for heat exchange(Patent Document 1), which is disposed in an atmosphere ofhigh-temperature gas and which performs heat exchange between a fluid tobe heated, which flows through the heat transfer pipe, and thehigh-temperature gas, wherein the heat transfer pipe through which thefluid to be heated flows has a three-layer structure in which the pipeis made of a heat-resistant alloy and an outer surface of theheat-resistant heat pipe is covered with a cover member made of aceramic-alloy composite material with a thermal expansion bufferinterposed therebetween, and the ceramic-alloy composite materialforming the cover member contains Al and AlN on condition that AlN is 1wt % or more and 90 wt % or less, and a total rate of (Al+AlN+AlON) is50 wt % or more and 100 wt % or less.

It is known that a fluorine-based resin has good corrosion resistanceand heat resistance to various chemicals. However, when the conveyingpipe is made of only the fluorine-based resin, the following drawbacksare caused because the fluorine-based resin is a poor heat conductor initself. Heat exchange efficiency is low, a longer time is taken to reacha predetermined temperature, and accuracy in temperature control at thepredetermined temperature is poor. Aiming to overcome those drawbacks,many proposals have been made in relation to, e.g., the technique ofcoating the fluorine-based resin over the surface of a metal having goodthermal conductivity. For example, a constituent member of equipmentusing gas is proposed in which at least two layers of coating films,containing a fluorine-based resin, are coated over a substrate (PatentDocument 2). The constituent member of equipment using gas is employedin, e.g., a heat exchanger having those coating films in which contentsof the fluorine-based resin are gradually increased and contents ofinorganic filler are gradually reduced from the lowermost layer film,coated over the substrate, to the uppermost layer film.

Furthermore, there are provided an aluminum alloy member having goodcorrosion resistance, and a plate-fin type heat exchanger or a platetype heat exchanger in which a heat transfer portion employing acorrosive fluid as a medium is formed using the aluminum alloy member(Patent Document 3). An underlying film made of organic phosphoric acidis coated over a surface of the aluminum alloy member used in theplate-fin type heat exchanger or the plate type heat exchanger includingthe heat transfer portion in which the corrosive fluid is used as themedium, and a coating film made of a fluorine-based resin paint havingan average film thickness of 1 to 100 μm after drying is coated over theunderlying film, whereby durability in adhesion of the coating films isimproved and high corrosion resistance to a corrosive fluid, e.g.,seawater, is obtained.

As described above, a method of coating a resin over a metal having goodthermal conductivity is generally proposed. However, because two typesof materials have different coefficients of thermal expansion, thecoating layers are less adaptable for expansion and contraction, andthey may peel off in some cases. This brings about the problem ofcausing corrosion of metal portions and contamination by metals, etc.Moreover, in the above-described method, the target fluid permeatesthrough pin holes in a resin coating portion, and the above-mentionedproblem is similarly unavoidable.

Carbon having good thermal conductivity and corrosion resistance isemployed in some cases. For example, there is proposed a block type heatexchanger using a method that is able to heat or cool a large amount ofan aqueous solution of hydrogen chloride, containing chlorine, by theheat exchanger without altering a heat transfer surface (Patent Document4). The heat transfer surface of the heat exchanger is made of carbonimpregnated with a fluorine-based resin, and the heat exchanger isconstituted by a block made of the carbon impregnated with thefluorine-based resin and arranged within a housing, the block includinga flow passage for the aqueous solution of hydrogen chloride throughwhich the aqueous solution of hydrogen chloride flows, and a flowpassage for a heat medium through which the heat medium flows.

A heat exchanger made of stainless steel can be used for a heat exchangetarget substance that is adaptable for a liquid contact portion made ofmetal. However, a thermal conductivity of stainless steel is relativelylow among metals, and a heat source having a large capacity needs to beused to obtain a certain level of heat exchange performance. This bringsabout the problem that the apparatus body is enlarged and powerconsumption is increased.

Although, as described above, many proposals trying to use variousmaterials in heat exchangers have been made with intent to obtain highcorrosion resistance and to increase the heat exchange efficiency, thereis still a demand for development of heat exchange technology that isadaptable particularly for a highly-corrosive substance to be subjectedto heat exchange, and that ensures high efficiency of heat exchange.

LIST OF PRIOR-ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent No. 3674401

Patent Document 2: Japanese Patent Laid-Open Publication No. 2004-283699

Patent Document 3: Japanese Patent Laid-Open Publication No. 2008-156748

Patent Document 4: Japanese Patent Laid-Open Publication No. 2006-289799

Patent Document 5: Japanese Patent Laid-Open Publication No. H9-280786

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In consideration of the above-described prior art, the present inventionprovides a heat exchanger that has high heat exchange performance andhigh corrosion resistance with respect to a heat exchange target fluid.

A prior-art heat exchanger generally employs a method of performing heatexchange by contacting a member, which is held in contact with a heatexchange target fluid during the heat exchange of the fluid, with a heatmedium such as a heat source or a coolant. A material of the contactmember is selected depending on characteristics the fluid. However, theselected material of the contact member does not always have goodthermal conductivity. In some cases, the disadvantage of the memberhaving low thermal conductivity has to be compensated for by employing,e.g., many electric heaters as heat sources, or an electric heaterhaving a large capacity. This often results in a decrease of energyefficiency in the heat exchange and an increase of the apparatus size.

The present invention is featured in that heat exchange can be performedat high efficiency even when the material of the contact portion isselected with attention focused only to characteristics of the heatexchange target fluid. In addition, according to the present invention,a compact product can be obtained at a relatively low cost withoutincreasing the apparatus size. An object of the present invention is toprovide a high-efficiency heat exchanger that can be applied to a widerange of fields regardless of the type of heat exchange target fluid.Another object of the present invention is to provide a heat exchangerin which corrosion of components caused by the heat exchange targetfluid is avoided, and the fluid having been subjected to the heatexchange is not contaminated. Still another object of the presentinvention is to provide a heat exchanger which has superior heatconduction characteristics in heating or cooling highly-corrosiveaqueous solutions and gases, e.g., hydrofluoric acid and hydrogenchloride, and alkaline aqueous solutions, e.g., sodium hydroxide. Stillanother object of the present invention is to provide a heat exchangetechnique that enables heat exchange to be performed at high efficiencywhile high purity of the heat exchange target fluid is maintained.

Means for Solving the Problems

The present invention is constituted by the following technical matters.

[1] A heat exchanger comprising a heat source, a heat transfer structurecontacting with a heat exchange target fluid, and a heat transfer memberthat transfers heat from the heat source to the heat transfer structure,thus performing heat-transfer type heat exchange through a contactsurface of the heat transfer structure with the heat exchange targetfluid, wherein the heat transfer structure includes a body having aninlet, an outlet, and a flow passage for the heat exchange target fluid,and many heat conductors mounted to the body, an inner wall surface ofthe flow passage for the heat exchange target fluid, the inner wallsurface defining a contact surface with the heat exchange target fluid,is made of a material stable against the heat exchange target fluid, theheat conductors are made of a material having a higher thermalconductivity than a material of the body, and the heat conductors aremounted near the flow passage for the heat exchange target fluid atpositions where the heat conductors are not contacted with the heatexchange target fluid.

[2] The heat exchanger according to [1], wherein the many heatconductors involve a plurality of heat conductors arranged in opposingrelation on both sides of the flow passage for the heat exchange targetfluid.

[3] The heat exchanger according to [1] or [2], wherein the heattransfer member comprises two heat transfer members sandwiching thebody, and one or more of the heat conductors extend from each of the twoheat transfer members. Here, the mode of extension of the heatconductors includes not only the case where the heat transfer member andthe heat conductors are formed integrally with each other, but also thecase where the heat conductors are mounted as separate components to theheat transfer member.

[4] The heat exchanger according to any one of [1] to [3], wherein theheat conductor has a pin-like configuration.

[5] The heat exchanger according to [4], wherein at least part of themany heat conductors is formed integrally with the heat transfer memberhaving a plate-like shape.

[6] The heat exchanger according to [4] or [5], wherein at least part ofthe many heat conductors has an outer surface of a zigzag configuration.Preferably, more than the half of the many heat conductors has the outersurface of the zigzag configuration.

[7] The heat exchanger according to [6], wherein the zigzagconfiguration is formed such that a surface area of the outer surface is1.5 to 3 times a surface area of the outer surface including noprotrusions of the zigzag configuration.

[8] The heat exchanger according to Claim [6] or [7], wherein the heatconductor having the outer surface of the zigzag configuration is ascrew.

[9] The heat exchanger according to [8], wherein the heat conductorhaving the outer surface of the zigzag configuration is a flat-headscrew.

[10] The heat exchanger according to any one of [1] to [9], wherein theflow passage for the heat exchange target fluid has a plurality of bentportions.

[11] The heat exchanger according to [10], wherein the flow passage forthe heat exchange target fluid has a returning bent portion for turningan extending direction of the flow passage to be returned toward aninlet side.

[12] The heat exchanger according to any one of [1] to [11], wherein atleast part of the heat conductors arranged on a side nearer to the inletis made of a material having a higher thermal conductivity than amaterial of the heat conductors arranged on a side farther away from theinlet. Here, the side nearer to the inlet implies, for example, a regionspanning ½, ⅓ or ¼ of an overall length of the flow passage from theinlet. The side farther away from the inlet implies a region similarlyspanning from the outlet.

[13] The heat exchanger according to any one of [1] to [12], wherein theheat conductors are arranged in a larger number and at a higher densityon a side nearer to the inlet than on a side farther away from theinlet.

[14] The heat exchanger according to [12] or [13], wherein the outlet isa discharge port in communication with outside.

[15] A heat exchanger wherein the heat exchanger according to any one of[1] to [13] is stacked plural.

[16] The heat exchanger according to any one of [1] to [15], wherein theinner wall surface of the flow passage for the heat exchange targetfluid is made of resin.

[17] The heat exchanger according to any one of [1] to [15], wherein theinner wall surface of the flow passage for the heat exchange targetfluid is made of metal or carbon.

[18] The heat exchanger according to any one of [1] to [17], wherein themany heat conductors involve heat conductors made of copper and heatconductors made of aluminum.

[19] The heat exchanger according to any one of [1] to [18], wherein theheat source is an exothermic source.

[20] The heat exchanger according to any one of [1] to [18], wherein theheat source is an endothermic source.

[21] A heat exchange method wherein heat-transfer type heat exchange isperformed with respect to a fluid by employing the heat exchangeraccording to any one of [1] to [20].

[22] A heat exchange method of performing heat-transfer type heatexchange with respect to a fluid by employing the heat exchangeraccording to [12], wherein the method comprises the steps of the heatconductors, which are made of a material having a relatively higherthermal conductivity than those on a side farther away from the inlet,on a side nearer to the inlet, and arranging the heat conductors, whichare made of a material having a relatively lower thermal conductivitythan those on a side nearer to the inlet, on a side farther away fromthe inlet, thereby variations in temperature distribution occurredbetween an upstream side and a downstream side of the flow passage forthe heat exchange target fluid are suppressed.

[23] A heat exchange method of performing heat-transfer type heatexchange with respect to a fluid by employing the heat exchangeraccording to [13], wherein the method comprises the steps of the heatconductors, which are made of a material having a relatively higherthermal conductivity than those on a side farther away from the inlet,on a side nearer to the inlet, and arranging the heat conductors, whichare made of a material having a relatively lower thermal conductivitythan those on a side nearer to the inlet, on a side farther away fromthe inlet, thereby variations in temperature distribution occurredbetween an upstream side and a downstream side of the flow passage forthe heat exchange target fluid are suppressed.

[24] A heat exchange method of performing heat-transfer type heatexchange with respect to a corrosive fluid by employing the heatexchanger according to [16].

From another aspect, the present invention is constituted by thefollowing technical matters.

(1) A heat exchanger comprising a flow passage through which a heatexchange target fluid flows, and a heat transfer structure that iscontacted with the heat exchange target fluid flowing through the flowpassage, thus performing heat-transfer type heat exchange through acontact surface of the heat transfer structure with the heat exchangetarget fluid, wherein:

(a) a surface of the heat transfer structure, the surface defining thecontact surface with the heat exchange target fluid, is made of amaterial stable against the heat exchange target fluid,

(b) heat conductors are mounted to the heat transfer structure, and aremade of a material having a higher thermal conductivity than a materialof the heat transfer structure, and

(c) the heat conductors are mounted near the contact surface of the heattransfer structure with the heat exchange target fluid at positionswhere the heat conductors are not contacted with the heat exchangetarget fluid,

whereby heat conduction efficiency is increased at the contact surfaceof the heat transfer structure with the heat exchange target fluid.

(2) The heat exchanger according to (1), wherein the heat conductor hasa pin-like configuration. Here, the pin-like configuration involves, forexample, not only a circular columnar shape and a polygonal pillarshape, but also the case where an outer surface of the heat conductorhas a zigzag configuration.

(3) The heat exchanger according to (1) or (2), wherein the heatconductor has a surface of a zigzag configuration.

(4) The heat exchanger according to any one of (1) to (3), wherein thecontact surface of the heat transfer structure with the heat exchangetarget fluid has a zigzag configuration.

(5) The heat exchanger according to any one of (1) to (4), wherein theflow passage for the heat exchange target fluid has a returningconfiguration to make the heat exchange target fluid turbulent and toincrease efficiency of heat transfer.

(6) The heat exchanger according to any one of (1) to (5), wherein theflow passage is constituted such that a diameter and/or an overalllength of the flow passage is changeable.

(7) The heat exchanger according to any one of (1) to (6), wherein theheat exchange target fluid is gas or a liquid.

(8) The heat exchanger according to any one of (1) to (7), wherein amaterial of the heat transfer structure is resin or metal.

(9) The heat exchanger according to any one of (1) to (8), wherein theheat conductor is made of metal having a higher thermal conductivitythan a material of the heat transfer structure.

(10) A heat exchange method of contacting a heat transfer structure witha heat exchange target fluid, thus performing heat-transfer type heatexchange through a contact surface of the heat transfer structure withthe heat exchange target fluid, wherein:

(a) a surface of the heat transfer structure, the surface defining thecontact surface with the heat exchange target fluid, is made of amaterial stable against the heat exchange target fluid,

(b) heat conductors are mounted to the heat transfer structure, and aremade of a material having a higher thermal conductivity than a materialof the heat transfer structure, and

(c) the heat conductors are mounted near the contact surface of the heattransfer structure with the heat exchange target fluid at positionswhere the heat conductors are not contacted with the heat exchangetarget fluid,

whereby heat conduction efficiency is increased at the contact surfaceof the heat transfer structure with the heat exchange target fluid.

(11) The heat exchange method according to (10), wherein the heatconductor has a pin-like configuration.

(12) The heat exchange method according to (10) or (11), wherein theheat conductor has a surface of a zigzag configuration.

(13) The heat exchange method according to any one of (10) to (12),wherein the contact surface of the heat transfer structure with the heatexchange target fluid has a zigzag configuration.

(14) The heat exchange method according to any one of (10) to (13),wherein the flow passage for the heat exchange target fluid has areturning configuration to make the heat exchange target fluid turbulentand to increase efficiency of heat transfer.

(15) The heat exchange method according to any one of (10) to (14),wherein the flow passage is constituted such that a diameter and/or anoverall length of the flow passage is changeable.

(16) The heat exchange method according to any one of (10) to (15),wherein the heat exchange target fluid is gas or a liquid.

(17) The heat exchange method according to any one of (10) to (16),wherein a material of the heat transfer structure is resin or metal.

(18) The heat exchange method according to any one of (10) to (17),wherein the heat conductor is made of metal having a higher thermalconductivity than a material of the heat transfer structure.

Advantageous Effects of the Invention

The following advantageous effects are obtained with the presentinvention.

Because acids and alkalis vigorously react with metals, the metalscannot be used in a portion contacting with the acids and the alkalis.For that reason, heat exchangers using resins in contact portions havebeen used so far. However, because thermal conductivities of resins arelow, thermal efficiency is poor, and an apparatus structure is increasedin size and complicacy. According to the present invention, a heatexchanger having high heat exchange efficiency and a compact structurecan be provided. Furthermore, since reaction between the heat exchangerand the heat exchange target fluid, such as acid and alkali, is avoided,temperatures of high-purity acid, alkali, etc. can be adjusted withoutcontamination by a trace ingredient. Moreover, the present invention canbe applied to other substances, such as high-purity water, than theacids and the alkalis regardless of whether the substances are in aliquid or gaseous state.

By utilizing fluid dynamics and thermodynamics and by employing thedirect heating method, the present invention can further provide a heatexchange technique, which ensures savings in electric power and space,and high heat exchange efficiency even when the portion contacting withthe heat exchange target fluid is entirely made of resin.

In addition, heat exchange performance of 80% or more is realized with aconfiguration to directly perform the heat exchange on condition thatthe portion contacting with the heat exchange target fluid ismetal-free. Thus, it can be said that the present invention provides aheat exchanger having prominent performance in comparison with the priorart.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating heat exchange by typicalindirect heating according to prior art.

FIG. 2 is a schematic view illustrating heat exchange by typical directheating according to prior art.

FIG. 3 is a schematic sectional view illustrating one example of a heattransfer-type heat exchanger using a plurality of independent heatconductors.

FIG. 4 is a schematic sectional view illustrating one example of a heattransfer-type heat exchanger in which a plurality of heat conductors isintegrated with a heat transfer plate.

FIG. 5 is a schematic sectional view illustrating one example of a heattransfer-type heat exchanger using a heat conductor that has a zigzagsurface configuration.

FIG. 6 is a schematic sectional view illustrating one example of a heattransfer-type heat exchanger in which a flow passage for a heat exchangetarget fluid has a zigzag shape.

FIG. 7 illustrates a sectional structure of a heat exchanger accordingto Embodiment 1 of the present invention; specifically, FIG. 7-1illustrates a section taken along a vertical plane (vertical direction),and FIG. 7-2 illustrates a section taken along a horizontal plane(horizontal direction).

FIG. 8 illustrates layout of an apparatus used for testing heat exchangeperformance.

FIG. 9 illustrates a temperature distribution confirmed by thermography,and represents that temperature rises in darker regions where the heatconductors are mounted, in comparison with the ambient temperature.

FIG. 10 illustrates a relationship between measured values of an outletgas temperature and a setting temperature, the relationship beingobtained from test results.

FIG. 11 comparatively illustrates heat exchange performance obtainedwith heat exchange through resin and heat exchange through a metalsurface according to the present invention.

FIG. 12 is a schematic sectional view to explain a zigzag configurationof the flow passage for the heat exchange target fluid; specifically,FIG. 12( a) is a sectional view to explain the case of doubling asurface area, and FIG. 12( b) is a sectional view to explain adjustmentof a pitch depth.

FIG. 13 is a schematic sectional view illustrating layout variations ofthe heat conductors. Specifically, FIG. 13( a) illustrates a layoutexample in which two heat conductors sandwiching a flow passage for theheat exchange target fluid therebetween are disposed to extend fromabove. FIG. 13( b) illustrates a layout example in which two heatconductors sandwiching the flow passage for the heat exchange targetfluid therebetween are disposed to extend from above and below. FIG. 13(c) illustrates a layout example in which four heat conductorssandwiching the flow passage for the heat exchange target fluidtherebetween are disposed to extend from above and below. FIG. 13( d)illustrates a structural example in which outer surfaces of the heatconductors in the layout example of the heat conductors in FIG. 13( a)have zigzag configurations. FIG. 13( e) illustrates a structural examplein which outer surfaces of the heat conductors in the layout example ofthe heat conductors in FIG. 13( b) have zigzag configurations. FIG. 13(f) illustrates a structural example in which outer surfaces of the heatconductors in the layout example of the heat conductors in FIG. 13( c)have zigzag configurations.

FIG. 14 illustrates structural examples in which the heat transfer plateand the plural heat conductors in FIG. 13 are formed integrally witheach other. Specifically, FIG. 14( a) illustrates a layout example inwhich two heat conductors sandwiching the flow passage for the heatexchange target fluid therebetween are disposed to extend from above.FIG. 14( b) illustrates a layout example in which two heat conductorssandwiching the flow passage for the heat exchange target fluidtherebetween are disposed to extend from above and below. FIG. 14( c)illustrates a layout example in which four heat conductors sandwichingthe flow passage for the heat exchange target fluid therebetween aredisposed to extend from above and below. FIG. 14( d) illustrates astructural example in which outer surfaces of the heat conductors in thelayout example of the heat conductors in FIG. 14( a) have zigzagconfigurations. FIG. 14( e) illustrates a structural example in whichouter surfaces of the heat conductors in the layout example of the heatconductors in FIG. 14( b) have zigzag configurations. FIG. 14( f)illustrates a structural example in which outer surfaces of the heatconductors in the layout example of the heat conductors in FIG. 14( c)have zigzag configurations.

FIG. 15 is an illustration to explain a temperature distribution whenheat conductors made of different materials are arranged; specifically,FIG. 15( a) depicts a plan view and a temperature distribution imagewhen heat conductors of the same type are arranged, and FIG. 15( b)depicts a plan view and a temperature distribution image when heatconductors made of different materials are mounted.

FIG. 16 is a plan view of a heat exchanger in which heat conductors arearranged at different densities between the upstream side and thedownstream side.

FIG. 17 illustrates a sectional structure of a heat exchanger equippedwith a shower head according to the present invention; specifically,FIG. 17( a) illustrates a section taken along a horizontal plane(horizontal direction), and FIG. 17( b) illustrates a section takenalong a vertical plane (vertical direction).

FIG. 18 is a side view of a multi-stage heat exchanger that isconstituted by stacking the heat exchangers each illustrated in FIG. 7.

FIG. 19 illustrates a configuration of a temperature-controlled supplyapparatus according to Embodiment 2 of the present invention.

MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a heat exchanger and a heat exchangemethod, the heat exchanger comprising a flow passage through which aheat exchange target fluid flows, and a heat transfer structure that iscontacted with the heat exchange target fluid flowing through the flowpassage, thus performing heat-transfer type heat exchange through acontact surface of the heat transfer structure with the heat exchangetarget fluid, wherein:

(1) a surface of the heat transfer structure, the surface defining thecontact surface with the heat exchange target fluid, is made of amaterial stable against the heat exchange target fluid,

(2) the heat transfer structure includes heat conductors that aremounted to the heat transfer structure, and that are made of a materialhaving a higher thermal conductivity than a material of the heattransfer structure, and

(3) the heat conductors are mounted near the contact surface of the heattransfer structure with the heat exchange target fluid at positionswhere the heat conductors are not contacted with the heat exchangetarget fluid,

whereby heat conduction efficiency is increased at the contact surfaceof the heat transfer structure with the heat exchange target fluid.

In the present invention, the heat conductors made of a material havinga higher thermal conductivity than that of the heat transfer structure(particularly, its portion contacting with the heat exchange targetfluid) are mounted in the heat transfer structure, which is made of asubstance (material) neither affecting nor affected by the heat exchangetarget fluid, at positions where the heat conductors are not contactedwith the fluid. The heat exchange target fluid can be efficiently heatedor cooled by heating or cooling the heat transfer structure andtransferring heat from a heat source to the heat exchange target fluid.

In general, liquids and gases having various characteristics areemployed as the heat exchange target fluids that are heated or cooled byheat exchangers. For example, aqueous solutions of acids or alkalis areused in chemical reactions, etching processes, and so on. However,because acids and alkalis vigorously react with metals, the metalscannot be used in a portion contacting with the acids and the alkalis inmany cases. Resins are used in some products of heat exchangers that areused for heat exchange of those reactive heat exchange target fluids.However, because thermal conductivities of resins are low, heat exchangeefficiency is poor, necessary electric power is increased, and shapesand structures of the heat exchangers are increased in size andcomplicacy in many cases.

The heat exchanger according to the present invention employs the directheating method and undergoes no limitations on materials of a surface ofthe heat transfer structure, the surface defining the contact surfacewith the heat exchange target fluid, insofar as the material is stableagainst the heat exchange target fluid. For example, a heat exchangerensuring savings in electric power and space and having good thermalefficiency of 80% or more can be provided regardless of that the portioncontacting with the heat exchange target fluid is entirely made ofresin.

[Heat Exchange Target Fluid]

The heat exchange target fluid used in the present invention is notlimited to particular one. Examples of the heat exchange target fluidare solutions or gases of corrosive acids such as hydrochloric acid,sulfuric acid, nitric acid, chromic acid, phosphoric acid, hydrofluoricacid, acetic acid, perchloric acid, hydrobromic acid, silicon fluorideacid, and boric acid, alkalis such as ammonia, potassium hydroxide, andsodium hydroxide, and metal salts such as silicon chloride, as well ashigh-purity water. Those heat exchange target fluids are used asmaterials to progress reactions with other substances, or chemicals,e.g., an etchant, employed in reaction steps, and they are used forintended purposes under control to proper temperatures by heatexchangers. The heat exchanger according to the present invention canperform heating, cooling, or temperature control of those heat exchangetarget fluids at high efficiency in a state free from contaminationcaused by trace impurities.

[Heat Transfer Structure]

The heat transfer structure used in the present invention has a surfacedefining the contact surface with the heat exchange target fluid, andheat conductors. The contact surface of the heat transfer structure withthe heat exchange target fluid is made of a material stable against theheat exchange target fluid. In other words, the material of the contactsurface is selected such that the surface of the heat transfer structureand the heat exchange target fluid will not react with each other in atemperature range where the heat exchange is performed, or thatingredients of the heat transfer structure will not elute from thesurface in such a temperature range. Reactivity (corrosiveness) of theheat exchange target fluid is different depending on the material of thesurface of the heat transfer structure, a contact temperature, etc.Furthermore, an allowable range of purity after the heat exchange isdifferent depending on the use and properties of the heat exchangetarget fluid. Therefore, the material of the heat transfer structurecannot be specified indiscriminately. In metal halides and etchants usedin manufacturing semiconductor devices, for example, because high-puritysubstances are employed, a reduction of purity attributable to the heatexchange process is not allowed. On the other hand, in heat exchangersfor turbines, a change in purity of the heat exchange target fluidattributable to the heat exchange process is insignificant in manycases.

The substance (material) of a member forming the surface of the heattransfer structure, which is contacted with the heat exchange targetfluid, is optionally selected from metals such as iron, carbon steel,stainless steel, aluminum, and titanium, synthetic resins such as afluorine-based resin and polyester, and ceramics. When highly-corrosiveacids are subjected to heat exchange, the fluorine-based resin ispreferably used. Examples of the fluorine-based resin arepolytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinylether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer(FEP), polychlorotrifluoroethylene (PCTFE),ethylene-chlorotrifluoroethylene copolymer (ECTFE),tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylfluoride (PVF),fluorinated polypropylene (FLPP), and polyvinylidene fluoride (PVDF).

In the heat exchanger according to the present invention, the heattransfer structure includes the heat conductors made of a materialhaving a higher thermal conductivity than that of the heat transferstructure (particularly, its portion contacting with the heat exchangetarget fluid). The heat conductors are mounted near the contact surfaceof the heat transfer structure with the heat exchange target fluid(i.e., near a flow passage for the heat exchange target fluid) at thepositions where the heat conductors are not contacted with the heatexchange target fluid.

One exemplary configuration of the heat transfer structure will bedescribed below with reference to FIG. 3. A heat exchanger 101illustrated in FIG. 3 includes a heat transfer structure 6 having a body61, heat conductors 62, a heater plate 51 serving as a heat source, heattransfer plates 52 a and 52 b, and a flow passage 7 for the heatexchange target fluid. Heat from the heater plate 51 is diffused intothe heat transfer structure 6 (including the body 61 and the heatconductors 62) through the heat transfer plates 52 a and 52 b. The body61 and the heat conductors 62 are heated by the diffused heat and, atthe same time, the heat exchange target fluid passing through the flowpassage 7 is also heated by the diffused heat through a contact surface63. Dotted-line arrows in FIG. 3 represent transfer of heat from thebody 61. Because the material of the heat conductors 62 has a higherthermal conductivity than that of the body 61, temperatures of the heatconductors 62 rise more quickly than that of the body 61, and the heatexchange with respect to the heat exchange target fluid can be performedefficiently. The heat conductors 62 are embedded in the body 61 in astate contacting with the heat transfer plate 52 a or the heater plate51. To increase efficiency of the heat exchange, the heat conductors 62and the flow passage 7 are preferably positioned as close as possible.An inner wall surface of the flow passage 7 is preferably a flat orcurved surface having no irregularities from the viewpoint ofmaintenance, but it preferably has a zigzag configuration from theviewpoint of increasing heat exchange performance.

As illustrated in FIG. 3, the heat conductors 62 each having a columnarshape can be mounted by individually inserting the heat conductors 62into holes formed in the body 61. Alternatively, as illustrated in FIG.4, the heat transfer plate 52 and the plural heat conductors 62 may beformed integrally with each other, and the heat conductors 62 may bemounted by collectively inserting the heat conductors 62 into holesformed in the body 61. The positions and the number of the mounted heatconductors 62 are determined in consideration of heat exchangeefficiency, etc. By increasing surface areas of the heat conductors 62,heat can be uniformly and efficiently diffused from the heat conductors62. The surface area of each heat conductor 62 is preferably increasedby forming the heat conductor 62 such that its outer surface has azigzag configuration as illustrated in FIG. 5. Stated in another way, anouter surface of the heat conductor 62 is preferably formed to have aconfiguration that annular mountains are continuously arranged in thelengthwise direction of the heat conductor 62 (i.e., a configurationthat mountains and valleys are alternately arranged in a continuousway). The “configuration that annular mountains are continuouslyarranged” involves the case where the mountains and the valleys arespirally formed like thread ridges and grooves. More preferably, thezigzag configuration is formed such that a surface area of the outersurface of the heat conductor 62 is, e.g., 1.5 to 3 times a surface areaof a column having the same diameter as the heat conductor 62, but notincluding the mountains (protrusions). When the body 61 is made ofresin, the heat conductor 62 having the zigzag configuration can bemounted in place by a method of mounting the heat conductor 62 in astate where the resin is still soft before hardening, and then hardeningthe resin, or a method of forming a hole in the hardened resin by, e.g.,a drill, and then screwing the heat conductor having the zigzagconfiguration into the hole. When the body 61 is made of metal, the heatconductor 62 is mounted by forming a hole with drilling in most cases.

FIG. 13 is a schematic sectional view illustrating layout variations ofthe heat conductors 62.

FIG. 13( a) illustrates a layout example in which two heat conductors 62sandwiching the flow passage 7 for the heat exchange target fluidtherebetween are disposed to extend from above. FIG. 13( b) illustratesa layout example in which two heat conductors 62 sandwiching the flowpassage 7 for the heat exchange target fluid therebetween are disposedto extend from above and below. FIG. 13( c) illustrates a layout examplein which four heat conductors 62 sandwiching the flow passage 7 for theheat exchange target fluid therebetween are disposed to extend fromabove and below. FIG. 13( d) illustrates a structural example in whichouter surfaces of the heat conductors 62 in the layout example of theheat conductors 62 in FIG. 13( a) have zigzag configurations. FIG. 13(e) illustrates a structural example in which outer surfaces of the heatconductors 62 in the layout example of the heat conductors 62 in FIG.13( b) have zigzag configurations. FIG. 13( f) illustrates a structuralexample in which outer surfaces of the heat conductors 62 in the layoutexample of the heat conductors 62 in FIG. 13( c) have zigzagconfigurations. In any of the configurations illustrated in FIGS. 13( a)to 13(f), the plural heat conductors 62 are arranged in opposingrelation on both sides of the flow passage 7 for the heat exchangetarget fluid.

In any of the configurations illustrated in FIGS. 13( a) to 13(f), aheat exchanger includes heater plates 51 a and 51 b, heat transferplates 52 a and 52 b, a body 61, and the flow passage 7 for the heatexchange target fluid. Because the above-mentioned components aresimilar to those in the heat exchanger 101 in FIGS. 3 and 5 except forincluding two heater plates, descriptions of those components areomitted here. It is to be noted that, in FIGS. 13( a) to 13(d), thelower heater plate 51 b may be dispensed with.

FIG. 14 illustrates structural examples in which the heat transfer plate52 and the plural heat conductors 62 in FIG. 13 are formed integrallywith each other. In any of the configurations illustrated in FIGS. 14(a) to 14(f), the plural heat conductors 62 are arranged in opposingrelation on both sides of the flow passage 7 for the heat exchangetarget fluid. Because the configuration illustrated in FIG. 14 issimilar to that illustrated in FIGS. 4 and 13 except that the heattransfer plate 52 and the plural heat conductors 62 are formedintegrally with each other, detailed description of the configurationillustrated in FIG. 14 is omitted here.

FIG. 15 is an illustration to explain a temperature distribution whenheat conductors made of different materials are arranged. Specifically,FIG. 15( a) depicts a plan view and a temperature distribution imagewhen the heat conductors 62 of the same type are arranged, and FIG.15(b) depicts a plan view and a temperature distribution image when theheat conductors 62 made of different materials are mounted.

In any of heat exchangers 104 illustrated in FIGS. 15( a) and 15(b), anumber 135 of mount holes into which the heat conductors 62 are insertedare formed in the heat transfer plate 52 and the body 61 (notillustrated) substantially at equal intervals. The heat conductors 62are each detachably mounted into the mount holes of the heat transferplate 52 and the body 61. For example, each heat conductor 62 may beformed in the shape of a screw having a flat head, and may be mounted tothe mount hole by screwing the heat conductor 62. A large number of heatconductors 62 may be constituted as a combination of heat conductors 62made of different materials. By combining the heat conductors 62 made ofdifferent materials, it is possible to eliminate variations in thetemperature distribution, which occur between the upstream side and thedownstream side of the flow passage 7. In addition, a manufacturing costcan be reduced by arranging the heat conductors 62 made of an expensivematerial only at necessary places, and arranging the heat conductors 62made of an inexpensive material at other places.

In FIG. 15( a), all the heat conductors 62 are formed of aluminum pins.In FIG. 15( b), the heat conductors 62 until the fifth column countingfrom left are formed of aluminum pins, and the heat conductors 62 afterthe sixth column counting from left are formed of copper pins. Stated inanother way, a number 135 of aluminum pins are mounted as the heatconductors 62 in FIG. 15( a), while a number 45 of copper pins aremounted as the heat conductors 62 on the upstream side and aluminum pinsare mounted on the downstream side in FIG. 15( b).

On the right side of FIGS. 15( a) and 15(b), temperature distributionimages are depicted. In FIG. 15( a), temperature is relatively low in aleft half and is relatively high in a right half. On the other hand, inFIG. 15( b), variations in the temperature distribution are eliminatedconsiderably. Thus, variations in the temperature distribution betweenthe upstream side and the downstream side can be reduced by arrangingthe heat conductors 62 made of a material having a high thermalconductivity on the upstream side, and the heat conductors 62 made of amaterial having a relatively low thermal conductivity on the downstreamside. With a reduction of the variations in the temperaturedistribution, distortions of the body, the heat transfer plates, etc.can be suppressed, and shortening of the heater lifetime can beprevented. Furthermore, in the case of treating a fluid that causesthermal denaturation when a temperature difference (ΔT) betweentemperature of the fluid passing through an inlet and temperature of thefluid passing through an outlet increases, it has been needed so far toheat the fluid to such an extent that an output is reduced not toexcessively increase ΔT. In contrast, high-efficiency heat exchange canbe performed with the heat exchanger according to the present inventionin which the variations in the temperature distribution are reduced.

FIG. 16 is a plan view of a heat exchanger 104 in which heat conductors62 are arranged at different densities between the upstream side and thedownstream side. In the heat exchanger 104 of FIG. 16, all the heatconductors 62 are formed of aluminum pins. The other configurations ofthe heat transfer plate 52, the body 61, etc. are similar to those inthe heat exchanger 104 of FIG. 15. In FIG. 16, nine heat conductors 62are arranged in the up-and-down direction until the fifth columncounting from left, and four or five heat conductors 62 are arranged inthe up-and-down direction in the sixth to fifteenth columns countingfrom left. Thus, the variations in the temperature distribution betweenthe upstream side and the downstream side can also be reduced byarranging the heat conductors 62 at a higher density on the upstreamside, and the heat conductors 62 at a lower density on the downstreamside. In the heat exchanger 104 of FIG. 16, the heat conductors 62 madeof materials having different thermal conductivities may be arranged onthe upstream side and the downstream side such that the variations inthe temperature distribution between the upstream side and thedownstream side are adjusted more finely.

FIG. 17 illustrates a sectional structure of a heat exchanger 105equipped with a shower head. Specifically, FIG. 17( a) illustrates asection taken along a horizontal plane (horizontal direction), and FIG.17( b) illustrates a section taken along a vertical plane (verticaldirection). The heat exchanger 105 equipped with the shower head has abody 61 including a heater plate 51, a heat transfer plate 52, many heatconductors 62, and a flow passage 7 for the heat exchange target fluid.Many discharge ports 75 communicating with the flow passage 7 are formedin the body 61. The heat exchanger 105 equipped with the shower headfurther includes two inlets 83 a and 83 b. A heat exchange target fluid73 having entered the flow passage 7 through the inlets is dischargedfrom the discharge ports 75 after being heated. Thus, in the heatexchanger 105 equipped with the shower head, the discharge ports 75communicating with the outside serve as outlets.

The many heat conductors 62 are constituted by copper-made pin-likemembers arranged on the upstream side nearer to the inlets 83 a and 83b, and aluminum-made pin-like members arranged on the downstream side,as in the configuration of FIG. 15( b), such that variations intemperature distribution over the entire length of the flow passage 7 isminimized. Stated in another way, the copper-made pin-like members aremainly arranged in regions closer to both the right and left sides ofthe body 61, and the aluminum-made pin-like members are mainly arrangedin a central region of the body 61. Furthermore, many bent portions 71are formed in the flow passage 7 such that the heat exchange targetfluid strikes against a flow passage wall in the bent portions 71 togenerate turbulent streams, thereby eliminating unevenness in heating.Accordingly, the fluids substantially at the same temperature aredischarged from the many discharge ports 75. While the heat exchanger105 equipped with the shower head is mainly used to provide a gas showerfor discharging gas, a liquid may be discharged in some cases.

The heat exchanger 105 equipped with the shower head may be constitutedin multiple stages by arranging one or a plurality of heat exchangersequipped with no shower heads in an upper stage, and by connecting twoinlets of the heat exchanger 105 equipped with the shower head to anoutlet of the heat exchanger in the upper stage through a branching pipe(see FIG. 18 described later).

FIG. 6 is a schematic sectional view illustrating principal parts of acylindrical heat exchanger 102 embodying the present invention. A heattransfer structure 6 including a heat conductor 62 and a body 61 isdisposed on an inner surface of a cylindrical heat source 5. The heatconductor 62 has a zigzag-shaped surface that is positioned on the sidefacing a flow passage, and a flat surface that is held in contact withthe heat source 5. The body 61 covers a surface of the heat conductor 62to define the flow passage 7, and it is contacted with the heat exchangetarget fluid. Here, the body 61 is preferably provided as a thin filmthat is formed on the surface of the heat conductor 62. A surface of thebody 61 contacting with the heat exchange target fluid is preferablyformed in a zigzag shape similar to that of the heat conductor 62. Theheat exchange efficiency at the body surface is improved by forming thebody surface in a zigzag shape so as to increase a contact surface area.

FIG. 12 is a schematic sectional view to explain a zigzag configurationof the flow passage for the heat exchange target fluid. Specifically,FIG. 12( a) is a sectional view to explain the case of doubling asurface area, and FIG. 12( b) is a sectional view to explain adjustmentof a pitch depth.

FIG. 12( a) illustrates an example in which an inner surface of the heattransfer structure 6 contacting with the heat exchange target fluid 73has such a zigzag configuration that regular triangles with one sidebeing 2 mm are continuously arranged along its cross-section. In otherwords, the inner surface of the heat transfer structure 6 has aconfiguration that annular mountains are continuously arranged in thelengthwise direction of the heat transfer structure 6. With the zigzagconfiguration described above, the surface area of the inner surface ofthe heat transfer structure 6 is increased twice that of a flat innersurface of the heat transfer structure not having the zigzagconfiguration. As a result, the heat exchange efficiency can be doubled.The zigzag configuration of the heat transfer structure 6 is not limitedto that illustrated in FIG. 12, and the present invention disclosed hereinvolves the case of forming the zigzag configuration such that thesurface area of the inner surface of the heat transfer structure 6 isincreased 1.5 to 3 times, for example.

While the heat exchange efficiency is increased as the surface area ofthe inner surface of the heat transfer structure 6 increases, it is notalways preferable to increase the surface area as far as possibledepending on properties of the heat exchange target fluid, such as aflow rate and viscosity. The left side of FIG. 12( b) illustrates astate where gaps 74 are generated between the inner surface of the heattransfer structure 6 and the fluid 73. In that state, becausenon-contact portions are generated between the inner surface of the heattransfer structure 6 and the fluid 73, the heat exchange efficiency isreduced. Thus, when generation of the non-contact portions due to thepresence of the gaps 74 is estimated, it is needed to make adjustmentnot to generate the non-contact portions by increasing the pitch (groovesize) of the zigzag configuration. The cylindrical heat exchanger 102may be constituted in a detachable manner, and the plural cylindricalheat exchangers 102 having different pitches may be prepared.

[Material of Heat Conductor and Distance Between Heat Conductor and HeatExchange Target Fluid]

The heat conductor 62 is made of a material having a higher thermalconductivity than that of the body 61. However, the expression “a higherthermal conductivity” implies a relative value in terms of comparisonbetween conductivities of both the materials, and it does not imply aspecific absolute value. The thermal conductivity is usually given asabout 0.2 W/m·k for plastic, about 0.25 for a fluorine-based resin,about 47 for carbon steel, about 15 for stainless steel, 237 foraluminum, 386 for pure copper, and about 1 for PYREX (registeredtrademark) glass, for example. From the above-mentioned materials,proper ones may be selected in consideration of relative thermalconductivities. Because the fluorine-based resin has a minimum value,the heat exchange efficiency is increased regardless of which one ofthose materials is selected as the heat conductor, when the body 61 ismade of the fluorine-based resin. When the material of the heat transferstructure 6 (body 61) is metal, specifically when the body is made ofstainless steel, a metal having higher thermal conductivity than thematerial of the heat transfer structure 6 (body 61), e.g., carbon steel,aluminum, or pure copper, can be selected as the material of the heatconductor. It is here to be noted that the substance (material) of theheat conductor preferably has a thermal conductivity as high aspossible.

There is known, e.g., a heat exchanger in which the contact surface 63of the heat transfer structure 6 with the heat exchange target fluid iscoated with the fluorine-based resin, and the body 61 is made ofstainless steel. For example, in the case of a plate made of stainlesssteel having a thickness of 8 mm with or without a corrosion-resistantcoating of the fluorine-based resin, a total heat transfer coefficientis measured as 1070 W/m²·k for the plate made of only the stainlesssteel, and 291 for the plate with the corrosion coating of 500 μm. Thisresult shows that an amount of transferred heat is reduced to ⅓ in thelatter plate. It is also reported that the heat transfer coefficient is845 when the plate is coated with the corrosion coating of 50 μm.

Accordingly, the distance between the heat conductor and the heatexchange target fluid is preferably as short as possible.

Embodiment 1 of Heat Exchanger

The structure of a heat exchanger according to Embodiment 1 of thepresent invention will be described in detail below. A heat exchanger103 illustrated in FIG. 7 has a parallelepiped shape with dimensions of150 mm×195 mm×34 mm (height). The heat exchange target fluid issubjected to heat exchange during a process of entering the heatexchanger 103 through an inlet connector (inlet) 81 and passing throughthe flow passage 7 for the heat exchange target fluid, which includesmany bent points (bent portions) 71 and 72, until flowing out from anoutlet connector (outlet) 82. The flow passage 7 is provided by forminga groove-like space in a body 61 in the form of a block made of afluorine-based resin. A number 172 of heat conductors 62 are mounted onboth sides of the flow passage 7 at intervals of 600 μm. The heatconductors 62 are each formed of a cross-recessed flat head machinescrew (i.e., a screw having a flat head) with a diameter of 3 mm and alength of 18 mm, and they are screwed into holes, which are formed inthe body 61 of the heat transfer structure 6, through a heat transferplate 52 a. Because those screws have flat upper surfaces, an uppersurface of the heat transfer plate 52 a can be made flush. A barrelportion of each screw where threads are formed preferably has a columnarshape that extends in the same diameter without tapering. By employing astandard screw as the heat conductor 62, the manufacturing cost of theheat exchanger can be reduced significantly. The present inventiondisclosed here involves the case of employing, e.g., a screw (copper) ofM3×20 m with a pitch of 0.5 mm or a screw (aluminum) of M4×12 mm with apitch of 0.7 mm in accordance with JIS standards.

A heat source (not illustrated) is disposed in contact with at least aregion of the heat transfer plate 52 a where the heat conductors 62 aredisposed. The heat source is preferably disposed in contact withrespective surfaces of both the heat transfer plates 52 a and 52 b. Theheat source is constituted, for example, as a stainless plate using, asan exothermic source, a nichrome wire with a heater capacity of 1600 W,or a mica plate using, as an exothermic source, a nickel alloy with aheater capacity of 4000 W. An exposed surface of the heat source ispreferably covered with a heat insulating material. More preferably, anoutermost layer of the heat exchanger 103 is entirely covered with aheat insulating material.

The heat transfer plate 52 b is physically coupled to the heat transferplate 52 a, and heat from the heat source is transferred to the heatconductors 62 and the body 61 through the heat transfer plates 52 a and52 b. The structural example of FIG. 7 employs a hollow parallelepipedstructure in which the heat transfer plate 52 a forms an upper surface,the heat transfer plate 52 b forms a lower surface, and a frame couplesboth the heat transfer plates to each other. The heat transfer plates 52a and 52 b (and the frame) may be made of the same material as that ofthe heat conductors 62, or of a material having a higher thermalconductivity than that of the heat conductors 62.

Because the heat conductors 62 and the flow passage 7 (i.e., the heatexchange target fluid) are positioned close to each other through aspacing of 600 μm therebetween, good thermal transfer is obtained. Theflow passage 7 through which the heat exchange target fluid passes hasdimensions of 6 mm width, 20 mm depth, and 1795 mm length, and includesmany bent points (bent portions) midway. In order to increase the numberof bent portions, it is preferable to provide not only bent portionswhich turn the extending direction of the flow passage by 180 degrees,but also a bent portion that turns the extending direction of the flowpassage to be returned. More specifically, in the structural example ofFIG. 7, a returning bent portion 72 for turning the extending directionof the flow passage by 90 degrees to be returned toward the inlet side(i.e., toward the side denoted by “IN”) is disposed to constitute twoflow passage systems A and B with intent to easily increase the numberof bent portions. The number of flow passage systems is not limited totwo as in the case of FIG. 7, and may be three or more. The heatexchange target fluid flowing through the flow passage strikes against aflow passage wall at the bent points (bent portions) to generateturbulent streams, thereby increasing the efficiency of heat exchangeperformed at the flow passage wall (contact surface). Preferably, aplurality of heat conductors is disposed between two flow passages 7arranged parallel to each other. Here, the expression “two parallel flowpassages” implies two flow passages that are arranged in such apositional relationship as denoted by 7 and 7 in FIG. 7. Speaking fromanother viewpoint, the flow passage 7 is preferably disposed to extendin a meander shape through gaps between the heat conductors 62 that arearranged substantially at equal intervals.

The heat exchange efficiency can be increased by coupling the pluralheat exchangers 103, each illustrated in FIG. 7, according to thepresent invention through connectors 81 and 82. The positions and thenumber of layers of the mounted heat conductors 62 can be determined onthe basis of practical studies on the heat exchange efficiency. In aregion where the temperature of the heat exchange target fluid is lowerthan the specified value, holes for mounting of the heat conductors 62may be newly formed in a corresponding region of the body 61 such thatthe heat conductors 62 can be additionally mounted in the relevantregion.

FIG. 18 is a side view of a multi-stage heat exchanger that isconstituted by stacking the heat exchangers 103 each illustrated in FIG.7. A multi-stage configuration can be obtained by connecting the inletconnector 81 of the heat exchanger 103 in an upper stage and the outletconnector 82 of the heat exchanger 103 in a lower stage through pipes 83a to 83 c. While an example of FIG. 18 illustrates a four-stageconfiguration, the multi-stage configuration is not limited to theillustrated example, and the number of stages may be set to two or moreoptional numeral. When the heat exchanger is of the multi-stageconfiguration as illustrated, the flow passage 7 is heated by not onlythe heat source positioned on the upper side, but also by the heatsource positioned on the lower side in the heat exchangers except forthat in the lowermost layer. In other words, in the example of FIG. 18,the heat transfer plate 52 b is heated by the heat source (heater plate)positioned on the lower side as well. When constituting the multi-stageconfiguration, a surface at which two stages are stacked is not coveredwith a heat insulating material such that the heat source positioned inthe lower stage and the heat transfer plate positioned in the upperstage are directly contacted with each other.

Thus, in the heat exchanger according to the present invention, thelength of the flow passage can be easily prolonged by employing themulti-stage configuration. Furthermore, the heat exchanger according tothe present invention is adaptable for various flow rates ranging from alarge to small rates by changing the diameter and the total length ofthe flow passage without modifying an internal structure to be matchedwith a flow rate of the heat exchange target fluid.

For example, when heat exchange is performed on condition of a flow rateof 10 L/min in terms of nitrogen gas, the heat exchange performance of80% or more can be obtained even with the body size being reduced to ½.The case of performing the heat exchange on condition of a flow rate of50 L/min or more is also adaptable by increasing the body size.

Embodiment 2 of Heat Exchanger

FIG. 19 illustrates a configuration of a temperature-controlled supplyapparatus 110 according to Embodiment 2 of the present invention. Thetemperature-controlled supply apparatus 110 includes a cooling-type heatexchanger 106, a cooling device 111, and pipes 112 a, 112 b, 113 a and113 b.

The cooling-type heat exchanger 106 includes a heat transfer structure6, and cooler plates 54 a and 54 b. The heat transfer structure 6 may bethe same one as that used in each of the heat exchangers 101 to 104.Flow passages through which a coolant circulates are formed to spreadover the entire insides of the cooler plates 54 a and 54 b. For example,an antifreeze solution or a gaseous coolant is used as the coolant. Thecoolant cooled by the cooling device 111 is supplied to the cooling-typeheat exchanger 106 through the pipe 112 a, and absorbs heat whilepassing through the cooling-type heat exchanger 106. After passingthrough the pipe 112 b, the coolant is returned to the cooling device111 and then supplied again to the cooling-type heat exchanger 106through the pipe 112 a. A heat exchange target fluid 73 (e.g., purewater) is supplied to the cooling-type heat exchanger 106 through thepipe 113 a, and is cooled while passing through the cooling-type heatexchanger 106. Thereafter, the coolant is discharged through the pipe113 b.

Practical examples of the present invention will be described below asExamples. It is to be noted that the following Examples merely representpractical examples, and that the present invention is not restricted bythe following Examples.

Example 1

The fact that the present invention can improve the heat exchangeefficiency was proved by employing a heat exchanger 12 having the sameconfiguration as that of the heat exchanger 103 illustrated in FIG. 7.

A test was conducted using an apparatus arranged as illustrated in FIG.8. Air 9 controlled in flow rate by a flow rate controller 10 wassupplied to a bubbling device 11, thus causing water to be contained inthe air 9. Then, the air 9 was passed through the heat exchanger 12. Theheat exchanger 12 was provided with a temperature controller 13 for anelectric heating panel, a device 14 for measuring an inner temperatureof PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and adevice 15 for measuring an outlet gas temperature to monitor the heatexchange. Moreover, a temperature distribution in the surface of thebody 61 was measured by thermography. FIG. 9 indicates the resultmeasured by thermography. In FIG. 9, a darker region represents a regionunder higher temperature. It was confirmed that the region under highertemperature was coincident with the mounted region of the heatconductors 62. It was also confirmed that a temperature distributionover the entire heat exchanger was not polarized and was uniform.

Example 2

In Example 2, an outlet temperature was measured by conducting testsover respective wide ranges of setting temperature and flow rate, i.e.,40 to 160° C. and 10 to 50 L/min respectively, by employing the sameapparatus as that used in Example 1. FIG. 10 depicts the measurementresult. It was confirmed that the heat exchange efficiency was 80% ormore over the wide ranges of setting temperature and flow rate. It wasalso confirmed that the heat exchanger according to the presentinvention was flexibly adaptable for the wide range of flow rate byemploying the same configuration without modifications.

Example 3

In Example 3, the performance of the heat exchanger according to thepresent invention in which heat transfer with respect to the heatexchange target fluid was performed through resin was compared with theperformance of the prior-art heat exchanger in which the heat transferwas performed through stainless steel, by employing the electric heatingpanel used in Example 1. In the present invention, humidified air wassubjected to heat exchange as in Example 1. On the other hand, in theprior-art heat exchanger, dried nitrogen was subjected to heat exchange.FIG. 11 depicts the comparison result. “Metal 30L” represents themeasurement result for the heat exchanger using stainless steel, and“Resin 30L” represents the measurement result for the heat exchangeraccording to the present invention. As seen from FIG. 11, the heatexchanger according to the present invention exhibits, even though thecontact portion is made of resin, the performance comparable to that ofthe prior-art heat exchanger using stainless steel.

Additionally, the tests were conducted on mist of H₂O in the heatexchanger according to the present invention, whereas the tests wereconducted on dried nitrogen in the prior-art heat exchanger. Because aircontaining water mist requires heat corresponding to latent heat ofwater, it is estimated that the heat exchanger according to the presentinvention has higher performance than the level depicted in FIG. 11.

INDUSTRIAL APPLICABILITY

The heat exchanger according to the present invention is superior inheat exchange performance, and it is able to prevent not only corrosionof the heat exchanger attributable to the heat exchange target fluid,but also contamination of the heat exchange target fluid caused by thecorrosion. The heat exchanger according to the present invention isfurther able to efficiently execute heating, cooling, and temperaturecontrol of corrosive chemicals and high-purity substances through heatexchange without causing corrosion and reducing purility of thehigh-purity substances. The present invention is useful to heat andcool, e.g., chemicals used in a semiconductor manufacturing processwhere high-purity substances are treated. The heat exchanger and theheat exchange method according to the present invention can be appliedto a wide range of fields as high-efficiency heat exchangers in heatingand evaporating apparatuses, cooling and condensing apparatuses, etc.,including chemical, pharmaceutical, food, textile, electric power, andnuclear power industries in which purity of products and corrosionresistance are required.

LIST OF REFERENCE SYMBOLS

-   -   1: resin pipe    -   2: inlet of heating target substance    -   3: outlet of heating target substance    -   4: heat medium    -   5: heat source    -   51: heater plate    -   52: heat transfer plate (heat transfer member)    -   53: heat insulating material    -   54: cooler plate    -   6: heat transfer structure    -   61: body    -   62: heat conductor    -   63: contact surface    -   7: flow passage for heat exchange target fluid    -   71: bent portion of flow passage for heat exchange target fluid    -   72: returning bent portion of flow passage for heat exchange        target fluid    -   73: heat exchange target fluid    -   74: gap    -   75: discharge port    -   8: connector    -   81: inlet connector (inlet)    -   82: outlet connector (outlet)    -   83: pipe    -   9: air    -   10: flow rate controller    -   11: device for bubbling air into water    -   12: heat exchanger    -   13: device for controlling and measuring temperature of electric        heating panel    -   14: device for measuring inner temperature    -   15: device for measuring outlet gas temperature    -   101 to 104: heat exchangers    -   105: heat exchanger equipped with shower head    -   106: cooling-type heat exchanger    -   110: temperature-controlled supply apparatus    -   111: cooling device    -   112 to 113: pipes

1-24. (canceled)
 25. A heat exchanger comprising a heat source, a heattransfer structure contacting with a heat exchange target fluid, and aheat transfer member that transfers heat from the heat source to theheat transfer structure, thus performing heat-transfer type heatexchange through a contact surface of the heat transfer structure withthe heat exchange target fluid, wherein the heat transfer structureincludes a body having an inlet, an outlet, and a flow passage for theheat exchange target fluid, and many heat conductors mounted to thebody, an inner wall surface of the flow passage for the heat exchangetarget fluid, the inner wall surface defining a contact surface with theheat exchange target fluid, is made of a material stable against theheat exchange target fluid, the heat conductors are made of a materialhaving a higher thermal conductivity than a material of the body, andthe heat conductors have a pin-like configuration and are mounted nearthe flow passage for the heat exchange target fluid at positions wherethe heat conductors are not contacted with the heat exchange targetfluid.
 26. The heat exchanger according to claim 25, wherein the manyheat conductors involve a plurality of heat conductors arranged inopposing relation on both sides of the flow passage for the heatexchange target fluid.
 27. The heat exchanger according to claim 25,wherein the heat transfer member comprises two heat transfer memberssandwiching the body, and one or more of the heat conductors extend fromeach of the two heat transfer members.
 28. The heat exchanger accordingto claim 25, wherein at least part of the many heat conductors is formedintegrally with the heat transfer member having a plate-like shape. 29.The heat exchanger according to claim 25, wherein at least part of themany heat conductors has an outer surface of a zigzag configuration. 30.The heat exchanger according to claim 29, wherein the zigzagconfiguration is formed such that a surface area of the outer surface ofthe zigzag configuration is 1.5 to 3 times a surface area of the outersurface including no projections of the zigzag configuration.
 31. Theheat exchanger according to claim 29, wherein the heat conductor havingthe outer surface of the zigzag configuration is a screw.
 32. The heatexchanger according to claim 30, wherein the heat conductor having theouter surface of the zigzag configuration is a screw.
 33. The heatexchanger according to claim 31, wherein the heat conductor having theouter surface of the zigzag configuration is a flat-head screw, andrespective upper surfaces of the heat conductors and of the heattransfer member are contacted with the heat source at a plane.
 34. Theheat exchanger according to claim 25, wherein the flow passage for theheat exchange target fluid has a plurality of bent portions.
 35. Theheat exchanger according to claim 25, wherein at least part of the heatconductors arranged on a side nearer to the inlet is made of a materialhaving a higher thermal conductivity than a material of the heatconductors arranged on a side farther away from the inlet.
 36. The heatexchanger according to claim 25, wherein the heat conductors arearranged in a larger number and at a higher density on a side nearer tothe inlet than on a side farther away from the inlet.
 37. The heatexchanger according to claim 34, wherein the outlet is a discharge portin communication with outside.
 38. The heat exchanger according to claim35, wherein the outlet is a discharge port in communication withoutside.
 39. A heat exchanger wherein the heat exchanger according toclaim 25 is stacked plural.
 40. The heat exchanger according to claim25, wherein the inner wall surface of the flow passage for the heatexchange target fluid is made of resin, metal, or carbon.
 41. The heatexchanger according to claim 25, wherein the many heat conductorsinvolve heat conductors made of copper and heat conductors made ofaluminum.
 42. The heat exchanger according to claim 39, wherein the bodyis made of resin or stainless steel.
 43. The heat exchanger according toclaim 25, wherein the heat source is an exothermic source or anendothermic source.
 44. A heat exchange method wherein heat-transfertype heat exchange is performed with respect to a fluid by employing theheat exchanger according to claim
 25. 45. A heat exchange method ofperforming heat-transfer type heat exchange with respect to a fluid byemploying the heat exchanger according to claim 34, wherein variationsin temperature distribution occurred between an upstream side and adownstream side of the flow passage for the heat exchange target fluidare suppressed by arranging, on a side nearer to the inlet, the heatconductors made of a material having a higher thermal conductivity thanon a side farther away from the inlet, and by arranging, on a sidefarther away from the inlet, the heat conductors made of a materialhaving a lower thermal conductivity than on a side nearer to the inlet.46. A heat exchange method of performing heat-transfer type heatexchange with respect to a fluid by employing the heat exchangeraccording to claim 35, wherein variations in temperature distributionoccurred between an upstream side and a downstream side of the flowpassage for the heat exchange target fluid are suppressed by arrangingthe heat conductors in a larger number and at a higher density on a sidenearer to the inlet than on a side farther away from the inlet.